Spindle for winding yarns in winding tubes or tubular winding cores

ABSTRACT

The spindle ( 1 ) comprises, in proximity of one end, an axial locking member ( 21 ) of the winding tube ( 3 ). The locking member can assume an active condition of axial locking of the tube as a result of rotation of the spindle and an inactive position when the spindle is not moving.

TECHNICAL FIELD

The present invention relates to devices for winding yarns and forming reels, bobbins or the like around winding cores or tubes.

More in particular, the present invention relates to an improvement to winding spindles, i.e. to the motorized shafts on which winding tubes or tubular winding cores are fitted torsionally to form therearound the reels or bobbins of yarn.

STATE OF THE ART

To wind a yarn, for example a yarn fed directly from an extrusion machine in the case of synthetic yarns, motorized spindles are utilized that rotate at high speeds. Winding tubes or tubular winding cores, around which the turns of yarn form, are inserted over these spindles. The yarn is wound using a yarn guide provided with alternate movement with at least one component substantially parallel to the rotation axis of the spindle and of the winding tube. Winding speeds are very high and the current tendency is towards a continuous increase in these speeds to increase production and consequently reduce the costs of the wound yarn package.

Torsional coupling between the spindle and the winding tube or core takes place by means of shaped profiles, for example polygonal in shape, so that the rotating spindle can drive the tube in rotation. The latter is generally constrained axially with respect to the spindle. For this purpose, in some cases conical collars are provided, inserted inside the winding tube or core, which engage by friction on the diameter of the spindle. In actual fact, as there are collars with different diameters, due both to construction and to wear, in the majority of cases the tube or core is constrained to the spindle only through the force of gravity.

With the increase in rotational speeds of the spindles, it is increasingly important to guarantee the safety of these machines. One of the problems that occurs, above all at high speeds, is given by the fact that the winding tubes or cores tend to vibrate and, as a result of these vibrations, can gradually slip off the winding spindles during forming of the reels of yarn. These vibrations are also due to the fact that the winding tubes or cores are at times dented and therefore not perfectly cylindrical.

OBJECTS AND SUMMARY OF THE INVENTION

An object of one embodiment of the invention is to provide a spindle for winding a yarn on a winding tube that completely or partly overcomes the aforesaid drawbacks.

According to one aspect, the invention provides a spindle for winding a yarn on a winding tube comprising, in proximity of an end of the spindle shaft, an axial locking member of the winding tube. The locking member can assume an active condition of axial locking of the tube as a result of rotation of the spindle and an inactive position when the spindle is not moving. This allows safe operation of the spindle, as without requiring any action by the operator, simple rotation of the spindle, for example above the minimum speed limit, causes activation of the locking member and therefore an intrinsic anti-slip off effect on the winding tube or core and relative reel being formed therearound. When the spindle is not moving the locking member returns automatically to the inactive condition and thus does not obstruct removal of the tube with the yarn package formed therearound and subsequent replacement with a new tube.

In a preferred embodiment of the invention, the axial locking member is activated through centrifugal force, against an antagonist force that tends to take the locking member to an inactive position, i.e. of release.

In a possible embodiment the axial locking member is elastically stressed in said inactive position. In a different embodiment, the axial locking member is taken to the inactive position by the weight of the locking elements. Centrifugal force acts on these locking elements when the spindle rotates to take the locking elements to an opened out position.

The locking elements can be radially expansible and arranged preferably in proximity of the end of the spindle, i.e. in the vicinity of the end part of the shaft of the spindle over which the winding tube or core is inserted.

In a possible embodiment the radially extractable or expansible elements can be composed of or comprise tabs oscillating about substantially horizontal axes, which are arranged in a retracted position as a result of the weight thereof when the spindle is not moving or rotates at a limited angular speed, and in an extracted position when the spindle rotates at a higher speed than a minimum angular speed.

In a different embodiment, the locking elements can be composed, for example, of levers or tabs housed in a housing inside the spindle, or more precisely in the shaft of the spindle, in proximity of the terminal end thereof. An elastic member can be provided to retain the elements in said seat. The elements can be constrained so that the elastic return force is overcome by the centrifugal force that acts on said locking elements when the spindle starts to rotate at an adequate speed. For example, the locking elements can be sliders that slide in radial housings with an elastic traction member that returns the sliders inside the radial seat of the spindle. In a different embodiment, the locking elements can comprise levers, arms or sliders articulated about axes substantially parallel to the axis of the spindle with a return spring that stresses them inside the respective housing produced in the spindle.

Further characteristics and embodiments of the spindle according to the invention are indicated in the appended claims and will be described in greater detail below on the basis of a non-limiting example of embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by following the description and accompanying drawings, which show a non-limiting practical embodiment of the invention. More in particular, in the drawing:

FIG. 1 shows a side view of a spindle,

FIG. 2 shows a partially sectional side view of a winding tube or winding core to be inserted over the winding spindle;

FIG. 3 shows a longitudinal section of the spindle of FIG. 1 with the tube of FIG. 2 inserted thereover;

FIG. 4 shows an enlarged detail of FIG. 3; and

FIG. 5 shows a cross section according to V-V of FIG. 4.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

With reference to the accompanying drawings, the number 1 indicates as a whole a spindle for winding a yarn about a winding tube or core, indicated with the number 3. The spindle is associated with a motor 5, which drives the spindle in rotation about a longitudinal axis A-A.

The spindle comprises a winding shaft 7 torsionally coupled to the motor 5 and presenting a base 7A having substantially cylindrical extension with a lower portion 7B that has, for example, a polygonal cross section or in any case non-cylindrical in shape to form a torsional coupling with respect to the winding tube 3, which is inserted over the shaft 7, 7A, 7B of the spindle 1. In this embodiment, the portion 7B with non-circular cross section is surrounded by a collar 9 which defines, together with the portion 7B, a recessed housing into which the lower end 3A of the winding tube or core 3 is inserted.

This winding tube presents, on the inside thereof, in proximity of the end 3A, a ring 11 defining an internal cylindrical surface with a diameter substantially equivalent to that of the base 7A of the shaft 7 of the spindle 1, to form a guide for centering the tube with respect to the spindle. Below the ring 11 the tube 3 has an internal surface 3B with a non-circular cross section complementary to the shape of the shaped portion 7B of the shaft 7 to form the torsional coupling between winding core or tube 3 and spindle 1.

At the upper free end opposite the base 7A the shaft 7 has an elastic gasket 13 which, in this embodiment, has an approximately toroidal shape. It would also be possible to use a gasket of different shape, such as an O-ring or a pair of O-rings, although a toroidal gasket is preferable as it allows problems of tolerance and positioning to be reduced. The gasket 13 can be made of rubber or other elastic material and can be stressed radially outward by elastic strips 15 (FIG. 4) located between the shaft 7 and the gasket 13. This gasket cooperates with a conical collar 17 snap-fitted inside the winding tube or core 3 in an axial position so that it corresponds with the casket 13 when the tube 3 is correctly inserted over the winding shaft 7 of the spindle 1. In this way, stabilization of the position of the winding tube 3 with respect to the shaft 7 of the spindle is achieved.

Above the gasket 13, the shaft 7 has a locking member, indicated as a whole with 21. In the embodiment shown, the locking member 21 comprises two tabs 23 pivoted about two axes 23A, substantially horizontal and approximately mutually parallel. When the spindle is not moving, the tabs 23 are in the idle position of FIG. 1. This position is assumed, for example, as a result of the weight of the tabs, which for this purpose can be suitable sized and, if necessary, made heavier. In the idle position of FIG. 1, the tabs 23 are contained inside a substantially cylindrical surface with diameter equivalent to or smaller than the minimum diameter of the conical surface of the collar 17 inserted inside the tube. For this purpose, the tabs 23 can, for example, be housed inside housings 25 provided in the shaft 7 (see in particular FIG. 4) in the form of corresponding flattened areas.

With the spindle 1 not moving or rotating at low speed the tabs 23 do not interfere with the insertion or removal of the winding tube or core 3 with respect to the spindle 1, since they are positioned oriented downward as a result of the weight thereof. The winding tube can therefore be inserted over the shaft 7 of the spindle 1 and subsequently removed therefrom together with the reel or bobbin of yarn B (FIG. 3) formed around the tube 3 without the tabs 23 obstructing these operations and without the operator requiring to perform any operations to deactivate the locking member 21.

Vice versa, when the spindle 1 is rotating at an adequate speed (which can also be substantially lower with respect to the normal operating speed), the tabs 23 tend to open out, assuming the position represented in FIG. 4 as a result of centrifugal force. Consequently, during winding of the yarn, the tabs 23 form an obstacle to axial removal of the winding tube or core 3. This prevents accidental removal of the winding tube 3 and of the bobbin being formed therearound due, for example, to vibrations imparted to the yarn package and to the tube 3 by conditions of dynamic unbalance or by any other external cause.

Activation of the locking member 21 takes place automatically simply as a result of rotation of the spindle. Therefore, once again the operator does not require to perform any operations to activate the locking member.

It is understood that the drawing only shows a non-limiting practical embodiment of the invention, which can vary in forms and arrangements, without however departing from the scope of the concept underlying the invention. Any reference numbers in the claims below are provided purely to facilitate reading thereof in the light of the description above and of the accompanying drawings and do not in any manner limit the scope of protection defined by the claims. 

1. A spindle for winding a yarn on a winding tube, the spindle comprising: a base; a free end opposite said base; an axial locking member of the winding tube, said axial locking member being in proximity of said free end, said locking member being able to assume an active condition of axial locking of the tube as a result of rotation of the spindle and an inactive position when the spindle is not moving, wherein said axial locking member is stressed in the inactive position through gravity and said axial locking member is activated in the locking position through centrifugal force.
 2. A spindle as claimed in claim 1, wherein said axial locking member comprises radially expansible elements associated with the free end of said spindle.
 3. A spindle as claimed in claim 1, wherein said axial locking element comprises tabs oscillating about substantially horizontal axes, said tabs being arranged in a retracted position as a result of the weight thereof when the spindle is not moving or said tabs rotating at a limited angular speed, and in an extracted position when the spindle rotates at a speed that is greater than a minimum angular speed.
 4. A spindle as claimed in claim 1, further comprising a gasket cooperating with a radial constraining surface provided inside the winding tube, said gasket being in a position axially retracted with respect to said axial locking member.
 5. A spindle as claimed in claim 4, wherein said gasket comprises a radial elastic expansion.
 6. A spindle as claimed claim 3, wherein said tabs are housed inside housings provided in the shaft in said inactive position.
 7. A unit, comprising: a winding tube; and a spindle comprising a base, a free end opposite said base and an axial locking member of the winding tube, said axial locking member being in proximity of said free end, said locking member being able to assume an active condition of axial locking of the tube as a result of rotation of the spindle and an inactive position when the spindle is not moving, wherein said axial locking member is stressed in the inactive position through gravity and said axial locking member is activated in the locking position through centrifugal force, wherein said winding tube has a conical collar snap fitted inside the winding tube in a position such that said axial locking member is arranged above said conical collar when said winding tube is fitted on said spindle.
 8. A spindle as claimed in claim 2, wherein said axial locking element comprises tabs oscillating about substantially horizontal axes, said tabs being arranged in a retracted position as a result of the weight thereof when the spindle is not moving or said tabs rotating at a limited angular speed, and in an extracted position when the spindle rotates at a speed that is greater than a minimum angular speed.
 9. A spindle as claimed in claim 2, further comprising a gasket cooperating with a radial constraining surface provided inside the winding tube, said gasket being in a position axially retracted with respect to said axial locking member.
 10. A spindle as claimed in claim 3, further comprising a gasket cooperating with a radial constraining surface provided inside the winding tube, said gasket being in a position axially retracted with respect to said axial locking member.
 11. A spindle as claimed in claim 8, further comprising a gasket cooperating with a radial constraining surface provided inside the winding tube, said gasket being in a position axially retracted with respect to said axial locking member. 